The present invention relates to a dissolvable frac plug that can be dissolved more rapidly when the plug is to be removed from the wellbore.
Downhole plugs are used in the extraction industry to seal off portions of wellbores for a variety of reasons. Portions of a wellbore may be sealed off to assist in the collection of hydrocarbons, to create pressure, or isolate zones of the well, for example. After the operation involving the downhole plug is complete, the plug must be removed from the wellbore or otherwise disposed of Various means of disposing of downhole plugs have been practiced over the years. Traditionally, such plugs were degraded or destroyed with mechanical means such as drilling or milling. But such operations can be complex, time-consuming, and expensive.
Dissolvable downhole plugs have been proposed to remedy the disadvantages of traditional plugs and facilitate plug retrieval or disposal. Typically, dissolvable plugs are made in part or whole of material that dissolves the plugs when they come into contact with certain elements such as water or other downhole fluids. After the plug is sufficiently dissolved, its remnants may be more easily retrieved for disposal. Dissolvable frac plugs are typically constructed with dissolvable alloys such as magnesium or aluminum, or polymers such as Polylactide/polyglycolide copolymers PGA, PLA or PLGA. These materials often require high temperatures as well as contacts with fluids having high salinity, high acidity, or other corrosive properties, to dissolve. However, high temperature, salinity, or acidity conditions may not be available at certain drilling sites. For example, in Permian basin wells, the lower temperature and salinity of the well fluids decreases their reactivity with dissolvable frac plugs and significantly increases the dissolution time. In such cases, a frag plug may not be sufficiently dissolved for removal after the frac procedure, requiring additional mechanical operations such as drilling or milling.
There is therefore a need for a dissolvable frac plug that can dissolve in insufficient or adverse downhole conditions. In particular, there is a need for a dissolvable frac plug that can enhance the corrosive properties of the downhole conditions where the frac plug is deployed. There is a further need for a dissolvable plug that can accelerate the dissolution process at the completion of frac plug operations.